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// AttributesImpl.java - default implementation of Attributes.
// http://www.saxproject.org
// Written by David Megginson
// NO WARRANTY!  This class is in the public domain.
// $Id: AttributesImpl.java,v 1.2 2004/11/03 22:53:08 jsuttor Exp $

package org.xml.sax.helpers;

import org.xml.sax.Attributes;


/**
 * Default implementation of the Attributes interface.
 *
 * <blockquote>
 * <em>This module, both source code and documentation, is in the
 * Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
 * See <a href='http://www.saxproject.org'>http://www.saxproject.org</a>
 * for further information.
 * </blockquote>
 *
 * <p>This class provides a default implementation of the SAX2
 * {@link org.xml.sax.Attributes Attributes} interface, with the
 * addition of manipulators so that the list can be modified or
 * reused.</p>
 *
 * <p>There are two typical uses of this class:</p>
 *
 * <ol>
 * <li>to take a persistent snapshot of an Attributes object
 * in a {@link org.xml.sax.ContentHandler#startElement startElement} event; or</li>
 * <li>to construct or modify an Attributes object in a SAX2 driver or filter.</li>
 * </ol>
 *
 * <p>This class replaces the now-deprecated SAX1 {@link
 * org.xml.sax.helpers.AttributeListImpl AttributeListImpl}
 * class; in addition to supporting the updated Attributes
 * interface rather than the deprecated {@link org.xml.sax.AttributeList
 * AttributeList} interface, it also includes a much more efficient
 * implementation using a single array rather than a set of Vectors.</p>
 *
 * @author David Megginson
 * @since SAX 2.0
 */
public class AttributesImpl implements Attributes {

  ////////////////////////////////////////////////////////////////////
  // Constructors.
  ////////////////////////////////////////////////////////////////////


  /**
   * Construct a new, empty AttributesImpl object.
   */
  public AttributesImpl() {
    length = 0;
    data = null;
  }


  /**
   * Copy an existing Attributes object.
   *
   * <p>This constructor is especially useful inside a
   * {@link org.xml.sax.ContentHandler#startElement startElement} event.</p>
   *
   * @param atts The existing Attributes object.
   */
  public AttributesImpl(Attributes atts) {
    setAttributes(atts);
  }

  ////////////////////////////////////////////////////////////////////
  // Implementation of org.xml.sax.Attributes.
  ////////////////////////////////////////////////////////////////////


  /**
   * Return the number of attributes in the list.
   *
   * @return The number of attributes in the list.
   * @see org.xml.sax.Attributes#getLength
   */
  public int getLength() {
    return length;
  }


  /**
   * Return an attribute's Namespace URI.
   *
   * @param index The attribute's index (zero-based).
   * @return The Namespace URI, the empty string if none is available, or null if the index is out
   * of range.
   * @see org.xml.sax.Attributes#getURI
   */
  public String getURI(int index) {
    if (index >= 0 && index < length) {
      return data[index * 5];
    } else {
      return null;
    }
  }


  /**
   * Return an attribute's local name.
   *
   * @param index The attribute's index (zero-based).
   * @return The attribute's local name, the empty string if none is available, or null if the index
   * if out of range.
   * @see org.xml.sax.Attributes#getLocalName
   */
  public String getLocalName(int index) {
    if (index >= 0 && index < length) {
      return data[index * 5 + 1];
    } else {
      return null;
    }
  }


  /**
   * Return an attribute's qualified (prefixed) name.
   *
   * @param index The attribute's index (zero-based).
   * @return The attribute's qualified name, the empty string if none is available, or null if the
   * index is out of bounds.
   * @see org.xml.sax.Attributes#getQName
   */
  public String getQName(int index) {
    if (index >= 0 && index < length) {
      return data[index * 5 + 2];
    } else {
      return null;
    }
  }


  /**
   * Return an attribute's type by index.
   *
   * @param index The attribute's index (zero-based).
   * @return The attribute's type, "CDATA" if the type is unknown, or null if the index is out of
   * bounds.
   * @see org.xml.sax.Attributes#getType(int)
   */
  public String getType(int index) {
    if (index >= 0 && index < length) {
      return data[index * 5 + 3];
    } else {
      return null;
    }
  }


  /**
   * Return an attribute's value by index.
   *
   * @param index The attribute's index (zero-based).
   * @return The attribute's value or null if the index is out of bounds.
   * @see org.xml.sax.Attributes#getValue(int)
   */
  public String getValue(int index) {
    if (index >= 0 && index < length) {
      return data[index * 5 + 4];
    } else {
      return null;
    }
  }


  /**
   * Look up an attribute's index by Namespace name.
   *
   * <p>In many cases, it will be more efficient to look up the name once and
   * use the index query methods rather than using the name query methods
   * repeatedly.</p>
   *
   * @param uri The attribute's Namespace URI, or the empty string if none is available.
   * @param localName The attribute's local name.
   * @return The attribute's index, or -1 if none matches.
   * @see org.xml.sax.Attributes#getIndex(java.lang.String, java.lang.String)
   */
  public int getIndex(String uri, String localName) {
    int max = length * 5;
    for (int i = 0; i < max; i += 5) {
      if (data[i].equals(uri) && data[i + 1].equals(localName)) {
        return i / 5;
      }
    }
    return -1;
  }


  /**
   * Look up an attribute's index by qualified (prefixed) name.
   *
   * @param qName The qualified name.
   * @return The attribute's index, or -1 if none matches.
   * @see org.xml.sax.Attributes#getIndex(java.lang.String)
   */
  public int getIndex(String qName) {
    int max = length * 5;
    for (int i = 0; i < max; i += 5) {
      if (data[i + 2].equals(qName)) {
        return i / 5;
      }
    }
    return -1;
  }


  /**
   * Look up an attribute's type by Namespace-qualified name.
   *
   * @param uri The Namespace URI, or the empty string for a name with no explicit Namespace URI.
   * @param localName The local name.
   * @return The attribute's type, or null if there is no matching attribute.
   * @see org.xml.sax.Attributes#getType(java.lang.String, java.lang.String)
   */
  public String getType(String uri, String localName) {
    int max = length * 5;
    for (int i = 0; i < max; i += 5) {
      if (data[i].equals(uri) && data[i + 1].equals(localName)) {
        return data[i + 3];
      }
    }
    return null;
  }


  /**
   * Look up an attribute's type by qualified (prefixed) name.
   *
   * @param qName The qualified name.
   * @return The attribute's type, or null if there is no matching attribute.
   * @see org.xml.sax.Attributes#getType(java.lang.String)
   */
  public String getType(String qName) {
    int max = length * 5;
    for (int i = 0; i < max; i += 5) {
      if (data[i + 2].equals(qName)) {
        return data[i + 3];
      }
    }
    return null;
  }


  /**
   * Look up an attribute's value by Namespace-qualified name.
   *
   * @param uri The Namespace URI, or the empty string for a name with no explicit Namespace URI.
   * @param localName The local name.
   * @return The attribute's value, or null if there is no matching attribute.
   * @see org.xml.sax.Attributes#getValue(java.lang.String, java.lang.String)
   */
  public String getValue(String uri, String localName) {
    int max = length * 5;
    for (int i = 0; i < max; i += 5) {
      if (data[i].equals(uri) && data[i + 1].equals(localName)) {
        return data[i + 4];
      }
    }
    return null;
  }


  /**
   * Look up an attribute's value by qualified (prefixed) name.
   *
   * @param qName The qualified name.
   * @return The attribute's value, or null if there is no matching attribute.
   * @see org.xml.sax.Attributes#getValue(java.lang.String)
   */
  public String getValue(String qName) {
    int max = length * 5;
    for (int i = 0; i < max; i += 5) {
      if (data[i + 2].equals(qName)) {
        return data[i + 4];
      }
    }
    return null;
  }

  ////////////////////////////////////////////////////////////////////
  // Manipulators.
  ////////////////////////////////////////////////////////////////////


  /**
   * Clear the attribute list for reuse.
   *
   * <p>Note that little memory is freed by this call:
   * the current array is kept so it can be
   * reused.</p>
   */
  public void clear() {
    if (data != null) {
      for (int i = 0; i < (length * 5); i++) {
        data[i] = null;
      }
    }
    length = 0;
  }


  /**
   * Copy an entire Attributes object.
   *
   * <p>It may be more efficient to reuse an existing object
   * rather than constantly allocating new ones.</p>
   *
   * @param atts The attributes to copy.
   */
  public void setAttributes(Attributes atts) {
    clear();
    length = atts.getLength();
    if (length > 0) {
      data = new String[length * 5];
      for (int i = 0; i < length; i++) {
        data[i * 5] = atts.getURI(i);
        data[i * 5 + 1] = atts.getLocalName(i);
        data[i * 5 + 2] = atts.getQName(i);
        data[i * 5 + 3] = atts.getType(i);
        data[i * 5 + 4] = atts.getValue(i);
      }
    }
  }


  /**
   * Add an attribute to the end of the list.
   *
   * <p>For the sake of speed, this method does no checking
   * to see if the attribute is already in the list: that is
   * the responsibility of the application.</p>
   *
   * @param uri The Namespace URI, or the empty string if none is available or Namespace processing
   * is not being performed.
   * @param localName The local name, or the empty string if Namespace processing is not being
   * performed.
   * @param qName The qualified (prefixed) name, or the empty string if qualified names are not
   * available.
   * @param type The attribute type as a string.
   * @param value The attribute value.
   */
  public void addAttribute(String uri, String localName, String qName,
      String type, String value) {
    ensureCapacity(length + 1);
    data[length * 5] = uri;
    data[length * 5 + 1] = localName;
    data[length * 5 + 2] = qName;
    data[length * 5 + 3] = type;
    data[length * 5 + 4] = value;
    length++;
  }


  /**
   * Set an attribute in the list.
   *
   * <p>For the sake of speed, this method does no checking
   * for name conflicts or well-formedness: such checks are the
   * responsibility of the application.</p>
   *
   * @param index The index of the attribute (zero-based).
   * @param uri The Namespace URI, or the empty string if none is available or Namespace processing
   * is not being performed.
   * @param localName The local name, or the empty string if Namespace processing is not being
   * performed.
   * @param qName The qualified name, or the empty string if qualified names are not available.
   * @param type The attribute type as a string.
   * @param value The attribute value.
   * @throws java.lang.ArrayIndexOutOfBoundsException When the supplied index does not point to an
   * attribute in the list.
   */
  public void setAttribute(int index, String uri, String localName,
      String qName, String type, String value) {
    if (index >= 0 && index < length) {
      data[index * 5] = uri;
      data[index * 5 + 1] = localName;
      data[index * 5 + 2] = qName;
      data[index * 5 + 3] = type;
      data[index * 5 + 4] = value;
    } else {
      badIndex(index);
    }
  }


  /**
   * Remove an attribute from the list.
   *
   * @param index The index of the attribute (zero-based).
   * @throws java.lang.ArrayIndexOutOfBoundsException When the supplied index does not point to an
   * attribute in the list.
   */
  public void removeAttribute(int index) {
    if (index >= 0 && index < length) {
      if (index < length - 1) {
        System.arraycopy(data, (index + 1) * 5, data, index * 5,
            (length - index - 1) * 5);
      }
      index = (length - 1) * 5;
      data[index++] = null;
      data[index++] = null;
      data[index++] = null;
      data[index++] = null;
      data[index] = null;
      length--;
    } else {
      badIndex(index);
    }
  }


  /**
   * Set the Namespace URI of a specific attribute.
   *
   * @param index The index of the attribute (zero-based).
   * @param uri The attribute's Namespace URI, or the empty string for none.
   * @throws java.lang.ArrayIndexOutOfBoundsException When the supplied index does not point to an
   * attribute in the list.
   */
  public void setURI(int index, String uri) {
    if (index >= 0 && index < length) {
      data[index * 5] = uri;
    } else {
      badIndex(index);
    }
  }


  /**
   * Set the local name of a specific attribute.
   *
   * @param index The index of the attribute (zero-based).
   * @param localName The attribute's local name, or the empty string for none.
   * @throws java.lang.ArrayIndexOutOfBoundsException When the supplied index does not point to an
   * attribute in the list.
   */
  public void setLocalName(int index, String localName) {
    if (index >= 0 && index < length) {
      data[index * 5 + 1] = localName;
    } else {
      badIndex(index);
    }
  }


  /**
   * Set the qualified name of a specific attribute.
   *
   * @param index The index of the attribute (zero-based).
   * @param qName The attribute's qualified name, or the empty string for none.
   * @throws java.lang.ArrayIndexOutOfBoundsException When the supplied index does not point to an
   * attribute in the list.
   */
  public void setQName(int index, String qName) {
    if (index >= 0 && index < length) {
      data[index * 5 + 2] = qName;
    } else {
      badIndex(index);
    }
  }


  /**
   * Set the type of a specific attribute.
   *
   * @param index The index of the attribute (zero-based).
   * @param type The attribute's type.
   * @throws java.lang.ArrayIndexOutOfBoundsException When the supplied index does not point to an
   * attribute in the list.
   */
  public void setType(int index, String type) {
    if (index >= 0 && index < length) {
      data[index * 5 + 3] = type;
    } else {
      badIndex(index);
    }
  }


  /**
   * Set the value of a specific attribute.
   *
   * @param index The index of the attribute (zero-based).
   * @param value The attribute's value.
   * @throws java.lang.ArrayIndexOutOfBoundsException When the supplied index does not point to an
   * attribute in the list.
   */
  public void setValue(int index, String value) {
    if (index >= 0 && index < length) {
      data[index * 5 + 4] = value;
    } else {
      badIndex(index);
    }
  }

  ////////////////////////////////////////////////////////////////////
  // Internal methods.
  ////////////////////////////////////////////////////////////////////


  /**
   * Ensure the internal array's capacity.
   *
   * @param n The minimum number of attributes that the array must be able to hold.
   */
  private void ensureCapacity(int n) {
    if (n <= 0) {
      return;
    }
    int max;
    if (data == null || data.length == 0) {
      max = 25;
    } else if (data.length >= n * 5) {
      return;
    } else {
      max = data.length;
    }
    while (max < n * 5) {
      max *= 2;
    }

    String newData[] = new String[max];
    if (length > 0) {
      System.arraycopy(data, 0, newData, 0, length * 5);
    }
    data = newData;
  }


  /**
   * Report a bad array index in a manipulator.
   *
   * @param index The index to report.
   * @throws java.lang.ArrayIndexOutOfBoundsException Always.
   */
  private void badIndex(int index)
      throws ArrayIndexOutOfBoundsException {
    String msg =
        "Attempt to modify attribute at illegal index: " + index;
    throw new ArrayIndexOutOfBoundsException(msg);
  }

  ////////////////////////////////////////////////////////////////////
  // Internal state.
  ////////////////////////////////////////////////////////////////////

  int length;
  String data[];

}

// end of AttributesImpl.java
